1. Technical Field
The present invention relates to a printing apparatus capable of printing both side surfaces of a medium that is transported.
2. Related Art
An ink jet type printer that includes a printing unit that prints images or the like on a sheet of paper, which is an example of a medium, by discharging ink, which is an example of a liquid, to the sheet has been known as a kind of printing apparatus. In such a printer, if a sheet is transported in a skewed manner to the printing unit from a portion of a transport path upstream of the printing unit, printing is not properly performed on the sheet, so that the print quality deteriorates. Therefore, in this type of printer, a site upstream of the printing unit along the transport path is provided with a register roller that performs a skew correction in which a leading end of a sheet transported from upstream of that site is caused to have firm or pressing contact with the roller so as to correct the skew, if any, of the sheet and then transports the sheet toward the printing unit (e.g., JP-A-2004-262574).
Such a related-art printer sometimes performs a two-side printing in which after a surface of a sheet is printed by discharging ink thereto, the reverse surface is also printed by switching back the sheet. Then, at the time of printing the reverse side in the two-side printing, the obverse surface of the sheet, which has been already printed by discharged ink, contacts the peripheral surface of the register roller. Therefore, at the time of the reverse-side printing, there is a risk that the peripheral surface of the register roller may become stained and then the stain may be transferred to another sheet that subsequently contacts the register roller.